1. Field of the Invention
The present invention relates to a thin film transistor and a flat panel display including the same, and more particularly, to a paraphenylene vinylene compound and a poly(para-phenylene vinylene) (PPV) compound for forming a buffer layer with a micro pattern, a thin film transistor that improves the alignment of an organic semiconductor layer using the PPV compound, and a flat panel display including the thin film transistor.
2. Description of the Related Art
Thin film transistors (TFTs), which are used in flat panel displays, such as liquid crystalline displays (LCDs), organic or inorganic light-emitting displays (or electroluminescent devices (ELDs)), and the like, act as switching devices that control the operation of pixels, and as driving devices that drive the pixels.
A TFT includes a semiconductor layer which includes source and drain regions doped with a highly concentrated impurity and a channel region formed therebetween, a gate electrode that is insulated from the semiconductor layer and disposed above the channel region, and source and drain electrodes corresponding to the source and drain regions, respectively.
Silicon TFTs including semiconductor layers formed of silicon have many disadvantages. For example, silicon TFTs have high manufacturing costs, can be easily broken by an outer impact, and must be manufactured at 300° C. or higher, which is not desirable for a plastic substrate.
Since a TFT is used as the switching device that controls pixels and as the driving device that drives the pixels in flat panel displays, such as LCDs, ELDs, and the like, which have become large, thin, and flexible, many attempts are being made to replace the conventional glass substrate with a plastic substrate. In order to use the plastic substrate, a low temperature process, not the high temperature process, is required.
This is possible when the semiconductor layer of the TFT is composed of an organic material. Thus, more active research into organic TFTs is being conducted.
However, when a plurality of organic TFTs are manufactured at the same time, the resulting organic semiconductor layers are non-uniform. That is, organic semiconductor layers of organic TFTs align in different directions, and thus, the organic TFTs have different threshold voltages and other characteristics.
Therefore, a flat panel display including organic TFTs fails to form precise, clear images corresponding to input image information.
According to US Patent Publication No. 2004-0056588, an excellent optical film can be formed using a poly(para-phenylene vinylene) precursor, thus obtaining an organic EL device with good brightness and high efficiency. However, US Patent Publication No. 2004-0056588 does not disclose a method of improving the alignment of the organic semiconductor. An improvement of the alignment of the organic semiconductor requires the development of a method of pattering a buffer layer.